Implement basic SIG management

[McPringle]

SIG = Special Interest Group

An SIG should have the following properties:

• id (unique)
• version
• name
• mission
• contact(s)

A contact should have the following properties:

• firstname
• lastname
• email
• company

The RESTful JSON API:

• POST /api/sigs: Create a new SIG (secured, admin only)
• GET /api/sigs: Get a list of all sigs
• GET /api/events/{id}: Get the event with the specified id
• PUT /api/sigs/{id}: Update the SIG with the specified id